youtubebeat/vendor/github.com/elastic/beats/winlogbeat/sys/buffer.go

63 lines
2.1 KiB
Go

// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package sys
// ByteBuffer is an expandable buffer backed by a byte slice.
type ByteBuffer struct {
buf []byte
offset int
}
// NewByteBuffer creates a new ByteBuffer with an initial capacity of
// initialSize.
func NewByteBuffer(initialSize int) *ByteBuffer {
return &ByteBuffer{buf: make([]byte, initialSize)}
}
// Write appends the contents of p to the buffer, growing the buffer as needed.
// The return value is the length of p; err is always nil.
func (b *ByteBuffer) Write(p []byte) (int, error) {
if len(b.buf) < b.offset+len(p) {
// Create a buffer larger than needed so we don't spend lots of time
// allocating and copying.
spaceNeeded := len(b.buf) - b.offset + len(p)
largerBuf := make([]byte, 2*len(b.buf)+spaceNeeded)
copy(largerBuf, b.buf[:b.offset])
b.buf = largerBuf
}
n := copy(b.buf[b.offset:], p)
b.offset += n
return n, nil
}
// Reset resets the buffer to be empty. It retains the same underlying storage.
func (b *ByteBuffer) Reset() {
b.offset = 0
b.buf = b.buf[:cap(b.buf)]
}
// Bytes returns a slice of length b.Len() holding the bytes that have been
// written to the buffer.
func (b *ByteBuffer) Bytes() []byte {
return b.buf[:b.offset]
}
// Len returns the number of bytes that have been written to the buffer.
func (b *ByteBuffer) Len() int {
return b.offset
}